Helix
by Satyrykal
Summary: As their nation is threatened by outside forces, a soldier and a spy make a reluctant alliance when they're discovered to be a Helix Pair. A mutation in their genetic code gives them the ability to harness untapped potential - but it requires synchronization with a compatible partner. Unfortunately, working together was more than either of them bargained for. Sci-fi Future AU.


**Cover Art by _FaintTwinkling_**

 **Beta'd by _MorriganFae_**

 **Characters Kidnapped from _Hiro Mashima_**

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 **CHAPTER 1 - Alpha**

 _2nd July, X7777_

The evening was sweltering as he dragged a slow breath of air through his lungs – hot and humid. The hair at his nape was sticky, sweat beading his neck and dampening the collar of his stuffy leather jacket. His shoulders flexed under the impeccably tailored fabric, the diagonal zip undone at the front to reveal a plain white shirt. He was hunched over a glass of whiskey, forearms braced against the wooden bar top as he drew idles swirls in the condensation forming on his coaster.

Normally he reveled in the heat, but Hargeon was another beast altogether – the seaport was known for its punishing weather.

His temple was furrowed in concentration, a scowl plastered across his lean face as his rosy fringe shaded his eyes – hiding the faint indentation of a missing piercing through his left brow.

 _"Could you look a little less miserable, flame-brain?"_

Natsu's grimace deepened, fingers reaching up to tug at his ear to straighten the communication piece concealed below his hairline.

"Shut up, ice dick." He murmured quietly, jaw tight as he tried to concentrate on his surroundings without drawing too much attention. The establishment he found himself in was plush and decadent – classic mahogany paneling and espresso upholstery – thick with the scent of cigars and alcohol.

He wriggled his nose, the spiced tobacco irritating his sinuses. It did nothing to help his present mood.

 _"Behave boys."_ The female voice was sharp despite the static of the radio, leaving no room for argument. _"Captain, the informant said the suspects would be here at the top of the hour. You just have to sit tight a little longer."_

"Why can't I just storm in after they arrive?" He grumbled, bringing his drink to his lips to mask his words. The amber liquid burned down his throat pleasantly. "I don't see why I gotta dress like some stogie."

There was a snort on the other side of the receiver, followed by a thump and a yelp. The pinkette bit back a laugh before Erza returned on the line. _"Because we don't know exactly who we're expecting – we don't want to give up our own operative and blow our cover for a small fry."_

Natsu sighed, shoulders slumping slightly as he resigned himself to his fate. Besides, despite his deviant streak, he wasn't one to disobey direct orders from his commanding officer.

"Yes ma'am." He responded before looking up and scanning the lounge once more. He might as well attempt to blend in properly, and it would be strange for him to sit there without a drink – even if he had no intention of downing it. With that in mind, he raised his hand to hail the barista, a fanged grin settling onto his features as he ordered a refill before closing his tab.

He held up his right wrist obligingly as the woman scanned the bar-code tattooed just below his pulse point. Her smile faltered as his name came into view, the army insignia flashed next to it on her screen as her eyes flickered over to his own. Natsu just met her gaze evenly, onyx irises swallowed up by the shadows in the dark room. She said nothing, choosing instead to return to polishing glasses on the far side of the counter.

There weren't many other patrons in the saloon – despite its luxurious décor, it was tucked within a side alley of a seedier neighborhood. It wasn't quite a harborside tavern, but it was still a far cry from the glass and chrome pubs in the city center.

In his peripheral, Natsu counted three men chatting idly a few meters away. Likely petty criminals, but not who he was looking for. He'd leave them for the civilian police, knowing it fell under their jurisdiction. He fought back the scowl he could feel twisting his lips – if he had his way, this entire mission would be left up to the local law enforcement as well. However, the decision came from above his pay grade.

The Brigadier had framed the Grimoire Syndicate as a military target, and there was no arguing with him.

It was a lazy evening, the melting sunset just visible from the windows on the western wall. The quiet was broken when the main door creaked open, tuscan rays spilling through the entryway. He blinked against the sudden light, pupils constricting as he took in the newcomer.

His breath instantly left him in one big gust, his heart in his throat.

She was ravishing.

She approached the bar on silver stilettos, her balance impeccable as his eyes unconsciously traced up the expanse of her long legs. The dress she wore was floor-length with a slit high at the top of her thigh – the midnight material stark and structured. There were two symmetrical geometric cutouts at her waist, enticing bronzed skin peeking through her cleopatra neckline – another jagged mesh opening visible by her left collar.

She passed by him, turning his head as he watched her sit with knees crossed, the slit of her skirt leaving her thigh exposed. His pulse jumped as he took in the naked back, partially concealed by the elegant gold curls cascading between her shoulder-blades.

He swallowed thickly as he tore his gaze away from her – cursing internally at his misfortune. It figured that a woman like her would saunter in while he was still on duty. _Shit luck_. At least Gray wasn't there to mock him. While the lenses in his eyes would capture the woman on neural camera, they couldn't reflect his reaction to her at the same time and he wasn't currently calibrated to a full-body _Nexus_.

"Where the fuck are these guys?" He muttered, fighting the urge to drum his fingers against the lacquered wood before him. He rolled his neck, cracking it lightly when he heard a feminine giggle. He furrowed his brows; the sound hadn't come from his radio.

He glanced over at the woman, who now had a wine-glass in hand, her tapered fingers wrapped around the stem as she brought it up to her scarlet-painted lips. Her mouth was pulled up at the corner, warm caramel eyes amused beneath her lashes.

Natsu did not have a chance to ponder it however, when his receiver stuttered back to life.

 _"There's movement on the street. Two men approaching your location, both match our target descriptions."_ Gray instructed, the telltale beeping on the keyboard sounding as he worked the monitor. Natsu grinned, spine straightening as leaned back – feeling the hard lines of his weapons strapped under his blazer.

Show time.

The door swung open once more as the suspects walked in, moving towards a secluded booth in the corner of the room. He swiveled on his stool slightly to get them in his sight-line when he sensed movement from beside him. Jasmine wafted in the air as the woman glided past, hips swaying as she joined the men who had just entered. That was unexpected.

He frowned.

 _"Focus idiot. We need to see their faces, not her ass."_ Came the wry reprimand. Natsu flushed, gritting his teeth.

"Piss off, frosty." He seethed but shifted. He concentrated so that his lenses would be able to verify the strangers' identities with the recognition software they had brought with them on the stakeout. It was set up back on their ship, which was the main reason Natsu had found himself inside – he didn't do well with transport unless he was the pilot. That and he got on the Major's nerves enough that she had already kicked him out.

The Titania was scary that way.

The girl was perched on the corner of the table instead of seating herself properly. She leaned over a muscular brunet as she murmured something in his ear. The other man, his grey hair coiffed, was smirking – a dangerous glint shining on his glasses as he placed a possessive hand high on the woman's thigh.

For the briefest of flashes – a moment so fleeting that Natsu thought he must have imagined it, she stiffened at the touch. Then she relaxed – fluttering her dark lashes at him as she tossed her flaxen locks over her shoulder, revealing a metallic banded choker adoring her slim neck.

He could see the men's eyes roving over every inch of her. Covertly he reached down and unsnapped his holster while straining to hear Gray's voice as it crackled down the line.

 _"We've got confirmation. Rustyrose and Azuma of Grimoire."_

"Finally, let's do this." Natsu cracked his knuckles, half rising before the radio turned on again.

 _"Hold on there, Captain. The file says there should be a third. He might still show up, we should wait."_ Erza warned, but the pinkette was already moving.

"A bit late for that." Natsu crowed, not bothering to keep his voice down as he drew out his stunner. At his cry, all three occupants of the booth turned towards him with wide eyes. His aim was true, catching the brunet on his sternum, toppling him over immediately.

The blonde darted out of range, launching herself to the side so her back was braced against the wall – the silver haired male scrambling up, drawing his own gun. Natsu twisted at the waist and ducked, anticipating the shot before it came – catching it against the adamantium vambrace at his wrist. It glanced off the metal with a screech before ricocheting into the bar – shattering the mirror above it.

The noise distracted him just enough to miss the door opening, his mind racing too fast to comprehend the warnings shrieking from his earpiece.

"What the _fu_ —"

Another gun fired, this time from behind him. It missed, going wide and hitting the opposite wall. At least he thought it did, until a sharp pain exploded by his ear – his receiver falling into his palm in pieces, covered in blood. The son-of-a-bitch had grazed him. He had lost contact, meaning his team would be frantic, running in here within minutes.

Great _._ The Titania coming in as cavalry meant his ass would be getting chewed out. _Again_.

He swore loudly, glowering at the newcomer. The blond man by the door had his pistol cocked, garnet eyes flashing in the low light as he ducked for cover.

Natsu moved, pivoting to kneel behind a toppled table so he could keep both opponents in his sights. The blond fired when the pinkette tried to rise. Rustyrose, who was only a few feet away, took advantage of the moment – racing forward to tackle the soldier.

Swearing, Natsu maneuvered forward instead of backing away in order to use his opponent's momentum against him. Pushing off his back legs, the pinkette flew forward with his arms braced, only to find the man crashing by his feet.

He blinked as he saw the mysterious woman crouched with her right leg extended, toes still pointed from her kick to Rusty's legs. She had toppled him easily. Natsu opened his mouth to thank her, only for her to beat him to it.

"He's getting away!" She screamed, waving an arm to the entrance as the blond slipped back out and into the street, scurrying away like a cockroach into the dampening sunlight.

 _Damn it._

She was right, but he couldn't leave a civilian alone with Grimoire operatives.

Rusty growled, lashing out but Natsu was faster. He caught the fist aiming for the woman's solar plexus in his own, twisting sharply so the creep crumpled back down to the floor. In a lighting movement, the pinkette had straddled the male's spine, digging in his knee to disarm him.

Yanking the grey-haired man's arm back, Natsu shoved his stunner between Rustyrose's shoulder blades, feeling the heat of the electricity kindle by his fingers as it zapped the culprit until he went slack. Natsu breathed heavily, blowing his coral locks out from his eyes and scanned the room. The soldier groaned when he realized the woman had escaped during the scuffle – the front door still open. Seconds later his team rushed in, dressed in their dark cargos and kevlar armour – their weapons locked and loaded, sweeping the area – ready to fire.

"One got away." Natsu called to them. Gray met his gaze with a sharp nod, racing back out the way he came – his partner Juvia hot on his tail.

The pinkette climbed off the limp body beneath him, taking the hand his commander offered to pull him up. He squeezed her fingers in thanks as he pulled cuffs out of his back pocket, securing them on Rusty's wrists while the Major did the same to Azuma a few feet away. Levy stood guard, watching for potential ambush, the other customers having bolted at the first sign of danger.

"We tried to warn you, but I assume you couldn't hear us after shots were fired." Erza told him, arms crossed as she leaned against a wall.

Natsu shrugged, grunting. "Yeah, no use crying over spilled milk though. At least we…"

He trailed off when his squad mates returned, the runaway woman behind them as they entered the bar. He let out a relieved chuckled, glad she was alright and that she hadn't been fleeing from them after all.

"Thanks for the help there, Miss. Couldn't have done it with—"

He was cut off abruptly as the blonde stormed up to him, stopping an inch from his face – the molten copper of her irises sparking dangerously as she prodded his chest with a manicured nail. It was filed to a sharp point. _Mavis_ , he didn't understand women's fashion. He was thankful he was wearing a vest.

"You let him get _away_!" She bellowed, punctuating each word with another jab at his torso. He batted her hand away and pushed at her shoulder to create some semblance of distance.

"What the hell? I saved you, crazy lady." He shot back. She lowered her arm but didn't move – unphased by his own towering form as he scowled down at her.

"Saved me?!" She shrieked, slack-jawed as she stared at him in utter disbelief. "The _nerve_. Rusty would have pinned you if I wasn't here. As if I need some hotheaded corporal—"

" _Captain_." He interrupted, pupils constricting as he ground his teeth – elongated canines visible between his lips as his eyes flashed – the jade ember-lit. "And just who the hell do you think you are?

She opened her mouth to respond, only to falter when laughter erupted behind them. Natsu glanced over at the same time she did, watching sourly as he found Gray doubled over as he guffawed, wiping undoubtedly fake tears from his eyes in long exaggerated swipes. Levy's mouth was twitching too, but she said nothing.

It was Erza who eventually came to his rescue.

" _That_ , soldier, is Lucy Heartfilia," Titania's eyes glittered as she waved a hand between him and the blonde, "She's Fiore Intelligence and our informant."

Well, _fuck_.

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 ** _"For the first week of Christmas my true love gave to meeeee..."_**

 **Hey guys!**

 **Happy December! Every week this month I will be debuting a new story - but this one is the prologue for my newest story 'Helix'! However, look out for the new ones since they actually run parallel to this one and are related.**

 **I am so excited for you guys to read it and hear what you think. Was it what you were expecting? What do you think of the Nalu dynamic? What about the various technology hints and futurescape? It's funny because I started this story before Eden's Zero was published but I'm noting a few similarities already ^.^**

 **I would like to take a moment to thank my epic beta _MorriganFae_ for all her help. She has been so kind as to go over not one, but FOUR of my stories! She is the best! I would also like to thank the phenomenal _FaintTwinkling_ , an artist of Tumblr who drew the cover art for this fic. She is so incredibly talented. You should go and check them both out!**

 **Your** _feedback_ **means a ton to me, and I always make a point to respond to all reviews and messages.** **Thanks for reading, Helix will be back in ' _Beta_ '.**

 **Cheers,**

 **Satyrykal**

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 **PS: Find me on** _Tumblr_ **or** _Twitter_ **for the latest on my stories and spamming reblogs of Fairy Tail content. Same username ^.^**

 **PSS: This is not a spoiler free story. Though it is** **an AU, this story references events up to the Alvarez arc, so continue at your own risk!**


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